Closed type burr



Dec. 19, 1967 P. B. JENSEN 3,358,547

cLosEn TYPE BURR Filed Nov. 23, 1965 United States Patent O 3,358,547 CLOSED TYPE BURR Philip B. Jensen, Naugatuck, Conn., assignor to Scovlll Manufacturing Company, Waterbury, Conn., a corporation of Connecticut Filed Nov. 23, 1965, Ser. No. 509,300 3 Claims. (Cl. 85-37) ABSTRACT F THE DISCLOSURE An improved one-piece metal burr to be secured to clothing by a rivet has a plain domed outer wall. A tapered hub is connected to the outer wall by a .back wall through a reverse bend and the back wall engages the under surface of the outer wall along a circumferential line to absorb pressure during the attaching operating without marring the outer domed surface.

This invention is an improved burr for receiving and holding a rivet. It is an improvement upon the burr disclosed in the patent to Maxim 2,574,436. Such burrs and rivets are commonly used in work clothes and play clothing for reinforcing the corners of pockets and other joints.

In the =burr of the Maxim patent, the outer wall was indented to provide a small central dome of such radius that it would help in preventing the angling of the tack, or skidding of the point of the tack during the clinching operation. Such skidding of the tack point would not only weaken the attachment, but the appearance is unsightly.

In the present invention, the skidding problem is solved without the expendient of indenting the top surface.

In my improved burr a rather steeply walled hub which is supported directly against the inner surface of the front wall. This not only affords an effective guide for the tack during the clinching operation, thus preventing its skidding, but also maintains adequate space for the upset end of the tack even on light materials.

In the accompanying drawing, I have shown for purpose of illustration, one embodiment which the invention may assume in practice. In the drawing:

FIG. 1 is a top plan view;

FIG. 2 is a central cross-section through the burr;

FIG. 3 shows the burr in association with a tack, ready to be attached;

FIG. 4 shows how the improved construction functions during the clinching operation; and

FIG. 5 shows the finished attachment.

My improved burr is of unitary sheet metal construction having a front Wall '6 with a continuous single-domed outer surface as distinguished from one which is indented or provided with openings.

The vburr has an annular backwall 7 which is joined to the outer edge of the front wall by a reverse bend in such a way as to provide a hollow rim section 8. This backwall is drawn .back against the front Wall 6 to provide a solid bearing in the region 9 where it engages the under surface of the domed outer wall along a circu-mferential line radially inward of said reverse bend. Extending from the inner edge of the backwall 7 is a solid-walled tapered hub 10 with an end opening 11. The wall of the hub 10 inclines at a rather sharp angle, perferably less than 40 to the vertical center line of the hu-b. As indicated, this angle is actually about 33, and thus the hub is strongly resistant to crushing by endwise pressure because of these comparatively steep walls and the bearing directly on the front wall in the region 9. It will be noted that the hub 10 at its base portion adjacent the back wall is approximately one-half the diameter of the front wall -6.

The tack has a head 12 covered with a smooth decorative cap 13 and a sharp pointed shank 14. The entrance opening 11 of the Iburr is of such size as to guide and give lateral support to the tack shank 14 during the clinching operation as seen in FIG. 4. This will prevent the skidding or angling of the tack which has proven to be such a problem. Furthermore, when the -burr is being clinched on the material M, the walls of the hub will resist endwise crushing pressure and maintain a suflcient chamber or space for receiving the upset end 0f the tack as seen in FIG. 5.

What I claim is:

1. A closed type burr of one-piece sheet metal construction comprising (a) a front wall with a continuous single-domed outer surface;

(b) an annular backwall joined to outer edge of the front Wall by a reverse bend so as to provide a hollow rim section whereby the back wall engages the under surface of said domed outer wall along a circumferential line radially inward of said reverse bend; and

(c) a solid walled tapered hub extending from said backwall inner portion and having an end opening for guiding a tack into the burr, said hub providing a cham-ber for receiving the upset end of such a tack.

2. A .burr as defined in claim 1, wherein said hub at its base portion adjacent said lbackwall is approximately one-half the diameter of said front wall.

3. A burr as defined in claim 1, wherein the angle between the Walls of said tapered hub and the center line of the hub is less than 40.

References Cited UNITED STATES PATENTS 1,800,768 4/ 1931 White 24-95 2,327,521 8/ 1943 Hart et al 24-95 2,442,362 6/ 1948 Janes 24-95 2,574,436 11/1951 Maxim 85-37 MARION PARSONS, JR., Primary Examiner. 

1. A CLOSED TYPE BURR OF ONE-PIECE SHEET METAL CONSTRUCTION COMPRISING (A) A FRONT WALL WITH A CONTINUOUS SINGLE-DOMED OUTER SURFACE; (B) AN ANNULAR BACKWALL JOINED TO OUTER EDGE OF THE FRONT WALL BY A REVERSE BEND SO AS TO PROVIDE A HOLLOW RIM SECTION WHEREBY THE BACK WALL ENGAGES THE UNDER SURFACE OF SAID DOMED OUTER WALL ALONG A CIRCUMFERENTIAL LINE RADIALLY INWARD OF SAID REVERSE BEND; AND (C) A SOLID WALLED TAPERED HUB EXTENDING FROM SAID BACKWALL INNER PORTION AND HAVING AN END OPENING FOR GUIDING A TACK INTO THE BURR, SAID HUB PROVIDING A CHAMBER FOR RECEIVING THE UPSET END OF SUCH A TACK. 